Does the food industry use drug-resistant yeasts?
A major cause of drug resistant clinical yeast infections is the same species that was previously considered non-pathogenic and is commonly used in the biotechnology and food industries. This is the drug-resistant yeast variety called Candida krusei.
In their current investigation, researchers from the University College Dublin in Ireland found that a drug-resistant yeast variety is one of the five most common causes of clinical yeast infections. The doctors published the results of their study in the English-language journal "PLOS Pathogens".
Yeast variety is responsible for increased morbidity and mortality
Candida krusei is a drug-resistant variety of yeast and one of the top five causes of clinical yeast infections. The experts say that this type of yeast is responsible for significantly increased morbidity and mortality in immunocompromised patients. In contrast, another type of yeast called Pichia kudriavzevii has so far been classified as safe because it has been used for centuries to produce food products such as cocoa, fermented milk and corn drinks. This yeast also plays an increasingly important role in the production of bioethanol and high-quality chemicals in biotechnology. So far, however, relatively few genetic or genomic studies have been carried out on strains of C. krusei and P. kudriavzevii, the authors of the study explain.
Two types of yeast are almost identical
In their investigation, the scientists sequenced the genomes of 30 clinical and naturally occurring strains of these two species. The results conclusively show that they are the same species, their genomes were 99.6% identical. In addition, the two species show similar levels of resistance to antifungal agents, the doctors say.
Industrial strains of yeast can cause disease
The results suggest that industrial strains of yeast are capable of causing disease in humans. The experts advise that caution should be exercised when using drug-resistant P. kudriavzevii strains for biotechnology and food applications.
Limits for drug resistance must be limited
It might be advisable to consider non-pathogenic Pichia types of yeast as possible alternatives for some industrial applications, explains study author Alexander Douglass from University College Dublin. The limits for the P. kudriavzevii strains, which are used in particular in the food industry, must be limited, the researchers say. If it were suggested that drug-resistant Candida albicans should be used in the production of food, this plan would be immediately rejected. The use of Candida krusei does not seem to bother anyone because the food manufacturers use a different name for it, explains study author Professor Ken Wolfe from University College Dublin. (as)